If CMLS (cultural multilevel selection) doesn’t help to explain human social evolution, how did human ultrasociality (ability to cooperate in huge groups of unrelated individuals) evolve? Steven Pinker falls back on the ‘usual suspects,’ kin selection and reciprocal altruism: “The huge literature on the evolution of cooperation in humans has done quite well by applying the two gene-level explanations for altruism from evolutionary biology, nepotism and reciprocity, each with a few twists entailed by the complexity of human cognition. … A vast amount of human altruism can be explained in this way.”
The problem with these two theories is that they cannot explain the evolution of human ultrasociality. Even in bands of hunter-gatherers the majority (three-quarters, according to recent estimates; Hill et al. 2011) are unrelated to ‘ego,’ and of course the average relatedness among huge societies of hundreds of millions of individuals is indistinguishable from zero. As to reciprocity, models show that it can work in small groups of few individuals, but it breaks down completely once the group size exceeds ten. This was clear to such eighteenth century thinkers as David Hume:
Two neighbors agree to drain a meadow, which they possess in common; because ’tis easy for them to know each other’s mind; and each must perceive, that the immediate consequence of his failing in his part is abandoning of the whole project. But ’tis very difficult and indeed impossible, that a thousand persons shou’d agree in any such action; it being difficult for them to concert so complicated a design, and still more difficult for them to execute; while each seeks a pretext to free himself of the trouble and expense, and wou’d lay the whole burden on others.
Although Pinker does not explicitly acknowledge this point, he seems aware that straightforward “nepotism and reciprocity” cannot explain extensive cooperation in groups of millions of people. Here’s where he brings in “cognitive twists.” The basic idea is that human propensities for cooperation with kin and in reciprocal settings are manipulated by other humans.
This is a version of the ‘big mistake’ hypothesis (as Boyd and Richerson have characterized this current in the Evolutionary Psychology theorizing), according to which people are somehow ‘fooled’ to cooperate with millions of other members of their society because they mistakenly consider them as relatives.
The version advocated by Pinker can be called the ‘Great Deception’ hypothesis. He uses this to explain away suicide terrorism. But what about volunteering for military service in times of war? Pinker writes, “Even in historical instances in which men enthusiastically volunteered for military service (as they did in World War I), they were usually victims of positive illusions which led them to expect a quick victory and a low risk of dying in combat.” But that does not describe the actual historical cases, e.g., volunteering by the British men during WWI. The British continued to volunteer long after it became abundantly clear that there will be no quick victory and that the war was a slaughterhouse. The British authorities did not need to implement the draft until 1916 (for a more nuanced discussion of this case, see my War and Peace and War).
Furthermore, a big part of Pinker’s argument is that it is “other humans” (presumably, political elites) who fool common people to fight and die to advance their nefarious ends. But there are many counterexamples. To give just one, the ruling elites of the Roman Republic (the senatorial class) bore their fair share (and perhaps even more) of the burden of Rome’s continuous warfare. The senatorial class fought and died on the front lines during the battles of the Second Punic War. Proportionately, the Senate lost more members than common citizens in such defeats as Lake Trasimene and Cannae. So who was fooling Roman patricians to sacrifice their lives for the sake of Patria?
There are many other examples in cultural evolution in which political elites (that is, the segment of the society that concentrates power in their hands) end up sacrificing their fitness. In a recent paper, Joe Henrich and coauthors analyze the spread of monogamy using the framework of cultural group selection. Without such a perspective it is very difficult to understand why would male elites agree to limit themselves to a single wife. Since the number of offspring left by a human male is determined primarily by the number of wives he has, one would expect that polygamy would greatly benefit wealthy and powerful males. Yet monogamy spread, and Henrich et al. make a credible case that it did so by the process of cultural group selection.
In the final analysis, research programs (sensu Lakatos) are judged by how productive they were. The CMLS framework has motivated a vibrant program of model development and empirical tests. The ‘Big Mistake’ and ‘Great Deception’ hypotheses of the Evolutionary Psychology have failed to lead to similar developments. It is not even clear to me how we could test Great Deception explanations empirically (can it be falsified?). In contrast, the young discipline of CMLS has already shown that it can generate testable (and empirically tested) predictions. In the end, I will not be surprised if the CMLS theory ends up completely transforming our understanding of human history.